Thrasher Termite & Pest Control of So Cal, Inc. in San Diego, California, recently discovered a new colony of Formosan subterranean termites in La Mesa, half a mile from the original 1992 outbreak of this destructive, invasive species. Formosan subterranean termites rapidly develop huge colonies and can cause significant structural damage within 6 months. This invasive species of termites  was last seen in La Mesa in 1998 and pose a serious threat to the La Mesa area. Conclusive identification of Formosan subterranean termites was made by Thrasher Termite & Pest Control in cooperation with the San Diego County Department of Agriculture and the California Department of Agriculture Plant Pest Diagnostics Division in Sacramento, California.

Formosan Subterranean Termite La Mesa Hot Spot Map 2018. Hot spot boundaries are within 1/2 mile of active infestations.

“It was clearly evident that these termites did not behave like native subterranean termites,” said Garrett Thrasher, owner and general manager of Thrasher Termite & Pest Control. The homeowner first noticed a potential problem when a cloud of winged insects swarmed their yard at twilight. Those winged insects turned out to be sexually mature Formosan subterranean termites seeking mates.

Formosan subterranean termites in cobwebs La Mesa 2018 (c) Thrasher Termite & Pest Control of So Cal, Inc.

“By the time we were called to the property, most of the termite reproductives were caught in spider webs, dead, or had disappeared. But we found a live, robust colony in the structure of the home,” said Thrasher.  “Unlike native subterranean termites, the termites we observed were extremely active, didn’t flee when disturbed, and the soldiers went into attack mode. They had hollowed out large areas of structural wood, always staying just beneath the exterior paint and unnoticed by the homeowner. All of these behaviors, in addition to size and coloration of the reproductives, led us to suspect Formosan termites. Unhappily, we were correct.”

Formosan subterranean termites seen in La Mesa 20 years ago. This new finding is very serious. While this Formosan termite population may be completely unrelated to the previous infestation, the  location suggests that Formosan termites have been hiding in plain sight for the last 20 years and have become very well established in La Mesa–and that much more challenging to eradicate.